RATP Group is a global leader in high-capacity urban rail, and the trusted partner of authorities in 16 countries across five continents, supporting them to make public transport the natural choice for passengers.
With 125 years of expertise, it has developed its know-how in the city of Paris’ ultra-dense network.
The company’s vertical integration over the years has enabled it to cover the full value chain, as asset owner and operator, design authority, project delivery entity (on brownfield and greenfield sites, including system integration) and the body responsible for day-to-day operations and maintenance.
As one of the world’s first metros, entering service in 1900, some of the Paris Metro network is well over a century old and features legacy stations. Rail Express found out more about how this has allowed RATP Group to develop its unique expertise in managing industrial heritage.
Craftmanship meets industrial expertise
RATP owns infrastructural heritage including 1000 kilometres of tracks for both metro and Réseau Express Régional (RER) trains, as well as 380 kilometres of underground and elevated structures, 900 escalators, 400 elevators, 2000 kilometres of high-voltage cables, and 368 metro and RER stations.
The rolling stock (approximately 6000 carriages) operated by RATP is the property of transport authority Île-de-France Mobilités. However, RATP is responsible for managing its life cycle, from procurement and network integration to maintenance, minor and major overhaul all the way to end of life.
The Group’s approach is to prolong the life cycle of heritage rolling stock and infrastructure as much as possible.
The teams in charge of maintaining and upgrading rolling stock and infrastructure over the long-term bring a “unique blend of craftmanship and industrial approach”, according to Sylvie Buglioni, Director of the Project, Technical and Industrial Management division for RATP Group.
“Rolling stock is initially purchased to last for approximately 35 years, but through our technical knowledge, we are able to extend its useful life to 40 or even 50 years,” she said.
Part of RATP Group’s role in managing the network’s infrastructure is ensuring rail safety and service quality over time.
“Managing the life cycle of our heritage is one of our top concerns,” said Buglioni. “Should replacements be identical? Or upgraded? How do you strike a balance between efficiency and history?
“Our goal is also to enable a more reliable and more intense service pattern – more frequent trains to welcome more passengers – which has led us to automate metro lines such as 1 and 4.
“Such expertise, which combines maintenance, operations and engineering, is an asset unique to the RATP Group.”
An example of a project that involved working with heritage infrastructure is the replacement of the Pont de Chartres bridge on the RER Line B.
The old bridge, which was constructed in 1923, was replaced in 2023 with the help of the largest crane ever used on a RATP construction site.
The crane, which was 107 metres tall and weighed 4544 tons, was transported to the site via 240 trucks, and took weeks to be assembled and dismantled.
“The new bridge offers more comfort for passengers, with new ballasted tracks that will reduce traffic noise and vibrations,” said Denis Masure, Managing Director of RATP Dev Australia and the former Head of RER B in Paris.
“The old bridge presented signs of wear and tear and decision was made to replace it to keep ensuring highest levels of safety, reduce noise levels and prepare for the arrival of new rolling stock.
“We have written part of the RER B Line’s long history while welcoming the arrival of new rolling stock at the same time.”
Maintenance on an operating network
RATP Group excels at improving the performance of an operating line by using cutting-edge systems and technologies, while factoring in the line’s history and the environment. Edgar See, Deputy Director International at RATP Dev and former Project Director of the Paris Metro Line 4 conversion to fully automated operations, said co-ordinating the maintenance of industrial heritage with other major projects on the network ensures optimum operational performance and provides passengers with the highest quality of service.
“As an example, we were able to adapt and strengthen platforms as part of the conversion of Line 4 to full automation while the line was in operation, to minimise disruption to customers.
“RATP Group honed this skill on the Paris network, and we now do the same for other complex maintenance works in its other networks all around the world.”
This expertise in co-ordinating maintenance and project delivery while managing an operating network is also highlighted by the renewal works on Line A of the RER, the busiest railway line in Europe, serving 1.3 million passengers every day.
The backbone of the Ile-de-France transport network on the East-West axis, it stretches 108.5 kilometres and serves the heart of Paris as well as linking the inner and outer suburbs.
RATP is responsible for maintaining the RER tracks, playing an essential role in the network’s success.
“The ballasted tracks of the central section of the RER Line A, which was put into service in the 1970s, were designed for daily tonnage and therefore mechanical loads, which have increased significantly over more than 40 years of operation,” said Mathilde Mahaut, Technical Bid Director at RATP Dev Australia and former Head of Safety at RATP Infrastructure.
“The tracks were experiencing several disorders which would have inevitably lead to degradation of rail safety conditions or availability.”
Inspections carried out in 2009 revealed that a complete renewal of the ballasted tracks in the central section was necessary to ensure that track maintenance was compatible with the operating requirements of this line, with the arrival of new double-deck rolling stock (MI09).
A total of 24 kilometres of track and 27 switchgears located on the central section of RER A between Vincennes and Nanterre Université stations were replaced.
“On an unprecedented scale, this work involved replacing all tracks, ballast and train switching systems,” said Mahaut.
“This operation was even more complex because on the central section, all trains run on two tracks under the tunnel, which made it impossible to carry out this work without interrupting traffic.”
To undertake the work with the least impact possible for passengers, service interruptions were scheduled during the summer months (July and August) from 2015 to 2021.
“July and August were chosen as summer is the least busy time of the year for the network. Alternative transport plans and a media campaign were systematically planned to alert the public.
“This included anticipating reinforcements on metro lines 1, 2, 3 ,6, 9 and 14 to ensure enough capacity on those lines to absorb RER A passengers.”
Embracing technology
While understanding the importance of history, RATP Group also embraces new technologies and equipment to ensure optimum infrastructure management.
One of the solutions it has implemented recently is Perceval, a robot dog developed for the inspection of tunnels and hard-to-reach areas. Equipped with a 360 degree pan, tilt and zoom (PTZ) camera with infrared sensor and radio equipment, Perceval has already carried out over 100 inspections and collected visual data of hard-to-reach infrastructure in a safe manner for employees. The robot allows for exhaustive monitoring of the condition of infrastructure and improved management.
Another solution RATP Group has been implementing to enhance safe working conditions for its maintenance teams is the use of exoskeleton equipment to minimise physical effort while employees carry out maintenance activities.
RATP Group has also developed in-house solutions like Maint’Up, an asset management system that gathers, centralises and analyses existing data from all its equipment to optimise maintenance and facilitate the daily work of its teams. By delivering the right information to each user via an ergonomic interface, the solution helps to optimise the frequency of maintenance operations, reduce the use of spare parts, improve upstream understanding of failures and speed up equipment troubleshooting. In doing so, Maint’Up contributes to reducing the total cost of ownership of equipment, facilitating maintenance operations as well as improving the reliability and performance of the network.
The Group has also fostered partnerships with start-ups and laboratories such as Rail Open Lab, to explore solutions to meet its needs and stay at the forefront of innovations.
An example of new technology that RATP Group has harnessed to improve rolling stock fleet management is digital twins.
Maintaining a fleet of 788 trains brings numerous challenges. RATP must continuously deliver updated training to its maintenance teams, optimise its workshops, prepare for the arrival of the new generation of rolling stock, and implement preventative maintenance.
“The use of digital twin technology can support these activities by connecting all of our data in a single space,” said Stephane Mousset, Asset Management Director for RATP Dev Australia.
“We can bring together the information from the train manufacturer, workshop designers, industrial equipment and maintenance team’s workflow in a single 3D model, which improves our infrastructure design and training processes.
“We can also use the technology to test elements in a virtual environment before they are implemented in the real world.”
Innovating with heritage in mind
Several stations on Line 14, the first fully automated Paris Metro line, have designs that nod to the 1970s, when the RER was built.
When the RER opened, RATP witnessed a boom in its ridership. To accommodate 50,000 passengers per hour between two locations, some metro platforms grew from 75 metres to 225 metres.
Instead of ordinary stations, cavernous cathedral-like stations were built to accommodate increasing passenger volumes. This started a new architectural trend that the stations on Line 14 would in turn adopt in the years leading up to 2000, from Bibliothèque Francois Mitterand to Saint‑Lazare.
To maintain each RER train station’s unique character, RATP has undertaken any necessary restoration work on a case-by-case basis.
“We want the stations to keep their own identities, so we look at each one individually and decide between upgrading them or preserving their heritage,” said Yo Kaminagai, Senior Expert in Urban Mobility Design and Former Head of Design for RATP.
“Auber Station, for example, was built in the 1970s and redefined underground urban planning at the time. However, it slowly lost its identity as elements were added over the years.
“Renovation works led Auber RER station into the 20th century, while revealing its intrinsic character and paying homage to its initial design.”
At Charles de Gaulle – Étoile station, another major hub on the RER A line, visual artists were consulted to give the station an upgrade in the form of a new colour scheme. The result was “bright but subtle” work on the mosaics that grace the station’s arched ceilings and walls, which passengers can admire along the escalator tunnels that connect the metro and RER lines.
“These renovations also focused on improving passenger information, a domain in which the RATP Group is recognised as a global leader.”
Heritage beyond transport
RATP is one of the last remaining active industrial players to operate maintenance workshops within the city of Paris.
To do this, RATP has transformed some of its spaces to accommodation urban densification.
For more than 30 years, RATP has been developing a restructuring and urban integration policy for its industrial sites.
As many of these sites were built at the beginning of the 20th century, they are no longer fit for purpose.
“Sprawling bus depots and maintenance workshops have been demolished and rebuilt, before being incorporated into ambitious programs that prioritise mixed use and social diversity,” said Céline Mazières, Director of Strategy, Marketing and Communication at Solutions Ville, the RATP Group subsidiary offering urban services including real estate to cities and local authorities.
“Such programs enable industrial activity to continue thriving in the city centre, preserving ‘blue collar’ jobs that have made new housing units, offices, shops, childcare centres and gardens a reality.”
Over the past few years, RATP’s Lagny, Jourdan and Belliard bus depots and Vaugirard and Italie maintenance workshops have benefited from this approach, which has allowed new neighbourhoods to spring up.
In total, seven metro workshops and bus depots have been transformed for mixed-use applications in conjunction with the BUS 2025 project, which is transitioning 4700 buses at 25 depots to zero emissions buses by the end of 2025.
